Many types of power turf mowing equipment are known. Such equipment can generally be classified as those mowers which include a rotary cutting unit(s) or those which include a reel cutting unit(s). A rotary cutting unit usually includes one or more rigid, generally straight, steel blades rotated within a housing about a vertical axis to sever grass or other vegetation at a predetermined height above the ground. A reel cutting unit, on the other hand, typically includes a frame within which is horizontally rotatably mounted a reel possessing a plurality of arcuate blades. The rotating reel blades pass in close proximity to a bedknife which spans the cutting unit frame parallel to the horizontal reel axis. Grass blades are sheared at the reel blade/bedknife interface.
While rotary cutting units are suitable for many purposes, it is generally perceived that reel units provide a higher quality cut. The present invention relates primarily to turf reel mowers, and the remainder of this discussion will focus on same. As is well known, another reel-like unit is used to produce a "verticut," and this type of cutting unit is also contemplated.
Power turf mowing equipment can also be categorized based on the method of propelling the cutting units. Generally, there are walk-behind, riding, and towed turf mowers. The present invention relates primarily though not exclusively to riding turf mowers, and for the sake of brevity the invention will hereafter be discussed in terms of commercial riding mowers having one or more reel cutting units.
Riding reel-type turf mowers typically include a traction vehicle supported by a plurality of wheels, including one or more traction wheels; a prime mover supported by the vehicle frame and connected through a transmission to the traction wheel(s); one or more reel-type cutting units, powered by the prime mover through belts or hydraulic motors, for example; one or more cutting unit lift arms pivotally mounted to the traction vehicle; a "pivot joint" between each lift arm and the vehicle; and a "cutting unit joint" between each cutting unit and its corresponding lift arm. Over the years, much effort has been directed to improving the quality of cut afforded by reel-type mowers. These efforts have been concentrated primarily in two areas, namely the cutting units themselves and the technique by which the cutting units are connected to the traction unit. The present invention relates in particular to a unique cutting unit suspension technique which can address any of a wide variety of cutting unit support problems, including but not limited to cutting unit "bobbing"; and providing a good "seal" between a floating cutting unit and a lift arm supported grass catcher. Each of these particular examples of problems which can be addressed by the cutting unit suspension technique of the present invention is discussed below.